Oracle 10g递归查询

Question

I have the following recursive query which would run in 11g but is not supported in Oracle 10g database:

with st as (
    select
        rownum id,
        case  
            when rownum-1 < 1 then null
            else rownum-1
        end parent_id,
        customer, 
        tickets
    from tickets
),
st2(id, parent_id, customer, tickets, offset) as (
        select
            id, parent_id, shuffler_id, subno, contrno, tickets, 0 offset
        from st
        where id = 1
    union all
        select
            st2.id, st2.parent_id, st2.tickets, (st.tickets + st.offset) offset
        from st, st2
        where st2.parent_id = st.id
)
select * from st2

What I'm trying to do is to calculate an offset for each row based on its previous row columns tickets and offset (same calculated column), and I'm starting the first row with an offset of 0; the fact that I need to depend on a column that I'm calculating during the execution of the query requires recursion.

The issue is the above query is not supported in Oracle 10g, so I tried to use connect by instead which works, but the ugly part is it's extremely inefficient:

with st as (
    select
        rownum id,
        case  
            when rownum-1 < 1 then null
            else rownum-1
        end parent_id, 
        customer,
        tickets
    from tickets
)
select
    id, 
    parent_id,
    customer,
    tickets,
    (
        select nvl(sum(tickets), 0) from st
        where level <  x.id
        start with id = 1
        connect by prior id = parent_id
    ) offset
from st x

Using the 2nd query I'm summing all the previous rows, which does the job but is redundant as well and I cannot depend on when this table grows to millions of records.

Any idea on how to implement something similar to the first query in Oracle 10g database?

Answer 1

  select 
    id, 
    customer,
    tickets,
    nvl(
      sum(tickets) over (
        order by id rows between unbounded preceding and 1 preceding
      ), 0) as offset
  from (    
    select
        rownum id,
        customer, 
        tickets
    from tickets
  )

or even more shorter (without introducing id s)

  select 
    customer,
    tickets,
    nvl(
      sum(tickets) over (
        order by rownum rows between unbounded preceding and 1 preceding
      ), 0) as offset
  from tickets